The present invention relates to a respiratory system for providing chemical and biological (CB) protection, ventilation, and delivering oxygen to a user and, more particularly, to a respiratory system that provides CB protection, ventilation, and delivers oxygen to an aircrew and that is self-contained and portable, and has provisions for providing either a flow of oxygen or a flow of air during the failure conditions of the ventilation and oxygen supplying systems.
Respiratory systems that provide CB protection, ventilation, and deliver oxygen to an a aircrew during ground and flight operations normally comprise a hood and mask assembly that cover the head and neck and has an optically clear face piece that covers the eyes of the aircrew. Such known respiratory systems suffer a drawback by requiring aircraft modifications, and by lacking provisions to accommodate for failure mode conditions of the ventilation and oxygen systems supplying the respiratory system, and by requiring multiple steps to select various operating modes. More particularly, these known respiratory systems do not provide continuous self-contained operation and allow the aircrew to be deprived of a flow of oxygen in the event of a failure of the oxygen supplying system or to be deprived of a flow of air in the event of a failure of the ventilator system. It is desired that means be provided for a continuous self-contained operation and to allow either a flow of air or a flow of oxygen to be delivered to the aircrew during the failure conditions involving either the oxygen or ventilation supply systems.